Transitioning from SS to tube amplification

Except during my early years in this hobby when monaural and vacuum tubes were the only choice, I've always used solid state amps and, mostly, electrostatic and ribbon panels. Recently, I bought a 20+ year old pair of good stand mount monitors (Reference 3A Serie MMC) that sounded very good with my solid state Peachtree pre and power amps so I thought it would be a good time to also try a vacuum tube amp in lieu of the many challenges associated with pairing tubes with my Martin Logan electrostatics speakers.

I started with a borrowed entry level but well reviewed Primary Luna Prologue One integrated amp paired with the Peachtree Audio Nova integrated as the preamp. I chose this combo because of the Peachtree's source input choices as well, of course, to use its remote control.

Because most of my listening is to various genres of solo guitar that's what I used to audition this combo. My first impression was mixed in that the sound seemed, at first, somewhat attenuated as if the strings had been muffled with a piece of cloth having been laid on the fret board. On the other hand, the sound was very pleasing with some of the jagged edges rounded off. Overall, and regardless of which might be argued as sounding most realistic, I'm very satisfied with what I'll call its more relaxed presentation. I like it and will very likely stay with the tubes.

Please don't read this as my support of one technology over another; first, I'm not qualified to make recommendations. Also, I'm 73 years old and have become more sensitive to certain sounds especially from percussive sources, so this becomes a factor in music choices as well as equipment.

Now that I've decided to stay with tubes, what I would like advice on is where to go next. I like this Prima Luna very much but have been advised by several whose advice I've learned to trust, that at 91dB these speakers may not be sensitive enough to get the best from the A3. I suppose what this means is that I need to look into another amp or more efficient speakers.
lol i had a primaluna pl2 and ran it with the Ref 3A de Capos, plenty loud.

I know use a 4 watt decware mini torii, loud enough but not LOUD. 10wpc is plenty with these speakers
Thanks, Grinnell. I really like these speakers and, so far at least, am pretty happy with the combination as described. I seldom listen at volumes that most would consider loud so, perhaps can keep the PL Prologue One. I currently have the preamp volume level set at 10 o'clock and the Prologue set at 9. Just to see what the results would be, I cranked the pre up to what I would call very loud. Because I heard no clipping, does this mean that the amp and speakers these speakers are compatible? I know that there are features built into their later models which make them somewhat more desirable but I'm wondering if there is any significant sonic difference.
Hi Jim (Broadstone),

I think I may have mentioned in one of your past threads that if the sensitivity of your Reference 3A speakers is comparable to that of the Reference 3A MM de Capo BE, per the measurements for that speaker shown here the 91 dB figure may be optimistic by around 5 dB or so.

Nevertheless, for solo guitar recordings, and for a considerable majority of recordings in most genres, I would certainly be surprised if the 35 watt capability of your amp proved to be insufficient.

A point to keep in mind is that what is usually the most significant factor in determining how much power is required is not volume or perceived loudness per se, but the dynamic range of the music that is being listened to. Meaning the DIFFERENCE in volume between the loudest notes and the softest notes, with well recorded minimally compressed classical symphonic music generally being one of the most demanding genres in that respect.

Many and probably most "pop" recordings, for example, are compressed to dynamic ranges of less than 10 db, which means that less than 10 times as much power will be required to reproduce the loudest notes as will be required to reproduce the softest notes. While many classical symphonic recordings will have dynamic ranges in the vicinity of 30 db (requiring 1,000 times as much power to reproduce the loudest notes compared to the softest notes), or in a few cases even more than 50 db (requiring 100,000 times as much power to reproduce the loudest notes compared to the softest notes; and no, that is not a typo).

For example, I have more than a few well engineered classical symphonic recordings in my collection which when played at modest average volumes of 75 db or so at my listening position, with the softest notes being in the 50 to 60 db area, will reach brief dynamic peaks of 100 to 105 db at the listening position. So most of the time the amplifier is putting out tiny fractions of a watt when playing those recordings, but brief dynamic peaks will require a great many watts.

From a subjective standpoint, though, loudness tends to be perceived based on the average volume of the music, not on the basis of brief dynamic peaks that may last for only a fraction of a second. Bear that in mind when considering Grinnell's comments.

Finally, with respect the 10 o'clock and 9 o'clock level settings you mentioned, keep in mind that those settings don't necessarily imply very much with respect to power. The relation between volume control settings and volume levels relates more to the gains and sensitivities of the equipment than to the maximum power and maximum volume capabilities of the equipment.

Best regards,
-- Al
Try setting the PL volume @ maximum and then adjust the PT's preamp volume accordingly.

I assume the PL does not have pre/out amp/in connections, which would be better.

Anyway, depending upon the PL's design, running its volume pot @ max should pretty much remove it (as much as possible) from the signal/music chain.
Post removed 
Yes, Al, I took your previous explanation to heart and found that the best example of dynamic range in my favorites collection Is I n the overture from Tannheuser relative to the relatively quiet lead in to the overwhelming brass. The range in this case, using an SPL meter, was about 50 dB starting at about 48. With the current setting on the Prologue the max volume is about 103 for this piece which is way more than I could take for very long. However, it sounded pretty accurate. Also, I reviewed the charts you referred to and the sensitivity is substantially lower than advertised and consistent with your previous comments. It's a disappointment but I can get by with it until I decide where to go next. I'm impressed with what Ive read about other PL amps and am tending toward staying with this manufacturer with one or another of their models, perhaps a dedicated power amp. For the music and volumes that I most listen to the current setup is quite satisfying. BTW, the mention of the clock dial setting was part of what the previous owner recommended to avoid clipping. In messing with various settings and volumes I've not been able to hear any so far.

Delay, thank you and I'm sure what you're saying makes good sense to those who have a better technical understanding of these things but I need a little more explanation to get my head around it. Also, what makes it a little more difficult is the fact that, right or wrong, I've always avoided maxing any controls thinking that that was an area where undesirable things start to happen. One thing I tried was to take that setting up to about 3 o'clock on the Prologue and at one point in a fairly loud playback I got a somewhat boomy sound of a lower mid frequency. Lowering the pre strength cured the anomaly

Steakster, it's good to hear that you had success with a similar setup and I thank you for sharing it. The bottom line here, I suppose, is that I truly like both the MMC's and the Prologue but I want to maximize within the constraints of my budget, of course, and need to decide which component to concentrate on. The most obvious or practical solution may be to find a more sensitive speaker.
An excellent speaker to consider is made by Audiokinesis, the Zephrin. It is easy to drive and very revealing.

As you are no doubt aware, dollar for dollar tube power is more expensive than solid state (and even in the 1960s cost/profit was the main impetus behind the switch to transistors) so speaker efficiency is very important when dealing with tubes!

Assuming your PL uses an Alps volume pot, turning it up to max will most likely offer the best sound as if will be the next best thing to removing it from the signal path completely.

I've done this with an Audion Silver Night integrated as well as with a Musical Fidelity X-A1 when adding a tube preamp to the integrated amps (neither had amp/out connections).

If you have ever used an integrated amp, or preamp with a tone control defeat switch the sonic benefits are similar.
Dekay, thanks, I understand now and it makes sense. Atmasphere, thanks for the advice but having just bought the ML Ethos speakers, the Reference 3 A's, and the Primaluna amp, I'm going to have to consider some less expensive fixes for awhile, at least.
OK, this is where I find myself with this issue. First, I spoke with a local audio dealer who used to sell the Reference 3A's and he confirmed what I'm reading here. These speakers have a sensitivity of 84-85 at best. That doesn't change how I feel about them, though; coupled with the PrimaLuna Prologue One they are, to me, up there with the best sound I can remember having in my home. I don't want to lose that very comfortable sound but I'm aware of the need of these speakers for more power to accommodate a wider dynamic range that Al has described on several occasions.

I have an opportunity to buy a used Rogue Audio Cronus Magnum for a very fair price which I know has quite a following and I've owned Rogue Audio solid state amps and think very highly of them. My concern is that I might lose something of what the Prologue delivers as regards it's smooth and comfortable sound. As a matter of fact, a local advanced hobbyist said that the Cronus has a noticeably "harsher" sound. Of course that is only one person's observation and one that might be cured with tube changes, I suppose.

Anyway, before I make another potentially questionable purchase, I'd like to hear what you all have to say. Thanks
If you can squeeze it the Rogue Pharoah would be hard to beat on paper with those speakers. Unless of course you prefer a softer sound you'd likely get with Cronus magnum or similar tube amp. It all depends on what kind of sound you are looking for.
Soft is definitely what I prefer. If it's necessary to achieve what I experience with the Prologue in a higher powered amp, I would even trade a little perceived resolution or detail to have it. I'd rather not, of course, but that's how hooked I've become on the so-called tube sound. I don't mean to infer that this type sound can't be achieved with SS, it's just that my research and conversations here lead me to believe that, in a general way, it's most likely to be found with tubes.

Try the volume pot settings I rec'd before purchasing other gear as the previous settings you mentioned may be the problem.

The PL should have more than enough power for the 3A's unless you have a large listening room (as you don't seem to listen @ high SPL's).

A good test would be to run the speakers with the PL (sans the PT) in order to see if the amp is capable of your expectations.
Dekay, I tried what you recommended, turning the PL volume control to 3/4 max and, thankfully, there was no perceptual difference compared to the settings that I originally described, at least in listening to solo guitar and string quartet. If there was a difference between the two settings it is with orchestral music. In this case, and I hope I'm using understandable language, when listening to Tannhauser the increased volume setting seemed to present somewhat better dynamics and an improved stage.

The bottom line is that I'm so attached to the sound of this amp/speaker combo that I don't want to risk losing it in a quest for more power. For example, and as previously discussed, I have a chance to purchase a Rogue Audio Cronus Magnum locally at a good price and, although my experience with Rogue hybrids has been very satisfactory, I'm afraid I'll lose what I have come to appreciate with the PL.
Just a clarification of my last post. I think what I may have observed re symphonic playback was psychological. I don't see how volume settings on the PL could affect dynamics in this setup. BTW, I'm auditioning a used Cary Audio Rocket 88 Tuesday. I don't know what to expect comparing it to the PL but I'll report my findings.
Broadstone, my rec was to turn the PL volume pot up to it's maximum setting (not ¾).
Dekay, yes, I know. I forgot to mention that I DID eventually go to 100% and the results posted were those observed at that setting. Sorry for the confusion.
Jim (Broadstone), having no experience with PrimaLuna, Rogue, or Cary products, I can't add too much at this point. What I can say, though, is that among medium powered tube amplifiers I and a goodly number of other audiophiles do have a particular affinity for EL34-based designs (that being the output tube supplied with the PrimaLuna Prologue One, of course, although it can accept other types as well). And keep in mind, also, that an increase from the 35W capability of that amp to the 100W capability of the Cronus Magnum is an increase of just 4.6 db. Certainly a substantial difference, but by no means one that I would characterize as huge.

Best regards,
-- Al
I think you should also recognize that the Rogue uses different tubes than the PL, KT 120s, that might be a little leaner in the midrange than the PL. I'd listen to it first before buying, I don't think it will have the classic tube sound that you so like in the PL. An excellent amp, but a different sound.

Sonically, I think you should consider trying the PL without using the preamp, though I do realize the advantage in convenience of the remote volume control.
Hi Jim

I would think you would require a 40-60 watt tube amp to achieve what you're looking for. I have a pair of MM Decapo BEs, the latest. While they have a benign impedance curve across the frequency spectrum they DO like power to come alive, at least for the music I listen to including a large dose of orchestral and large scale. You didn't specify your room size which would also come into play as well. The fact that the music sounds a bit attenuated like lean maybe? Well I'm not sure what is causing that impression, maybe the integration of the Prima Luma with the Peachtree?. While I've never listened to a pair of the older MMs I would expect the electrical characteristics of the current model and yours would be very similar.

As a few points of reference for your information going forward, I have 3 tube amplifiers in house and have tried several other both tube and SS amplifiers and several other various pre-amps in my quest to find the magic combination to realize the potential of the speakers. As of right now it is the Quicksilver Silver 88 with Kt 150 tubes and a highly upgraded/modified vintage Conrad Johnson PV9a pre-amp that I gambled on mainly because of it's large power supply and build quality. This has proved a very synergistic pairing, being able to play large scale music in a very convincing and natural manner and yet play at very low levels while retaining the resolution and natural dynamic shifts in the music, the best of both worlds. I would definitely consider the Quicksilver line as well. Reasonably priced, very low distortion, quiet, simple design but importantly they are full and natural sounding in the mid/upper bass area where I find variation among tube amplifiers. In addition they don't exaggerate the upper frequencies which can become fatiguing over long term listening. I'm sure there are others that will work as well but I can confidently recommend the Quicksilver line. The mid-monos are also excellent at 60 watts and I would expect would work quite well for your stated needs plus they are quite reasonably priced. Good Luck!
I own a Prima Luna Premium, bought the premium version because the base version does sound "soft" on plucked strings. The premium and dialog versions use better/faster diodes in the power supply rectifier bridge which makes the sound crisper. As to power, you can beef that up easily with KT-120 and KT-150 tubes, much better gthan KT-88's in a Prima Luna.
Tubegroover, thanks. I'm very early into this tube amplification quest and appreciate all advice especially when it comes to specific types and brands and what to expect from them. From what I've read and heard, I think you're right, The DeCapos and my speakers do have similar specs. I actually haven't found any shortcomings with these yet and haven't even experienced higher volume issues which was what I've been told to watch out for. My room is about 20X26X9 with my listening position about 16' from the speaker plane. I listen primarily to solo guitar, string quartet, light jazz and occasional orchestral music. I listen at fairly moderate volume.

My reference to attenuation of sound relative to what I'm used to, was not a complaint; I actually find it to be less fatiguing and more comfortable listening. To some extent it's also what I'm looking for in future purchases. Coincidentally, Davide, I actually used the plucked string example to explain the characteristic that described the difference between these two technologies to my wife. As an exaggerated example, I asked her to imagine the difference between plucking guitar strings with a plastic or felt pick.

Even though I'm sure I'll continue with tubes I'm not supporting one technology over another. In this case the decision is quite personal; age related hearing issues persuade me in this new direction as some sounds, especially those with percussive origins, cause me significant discomfort.
Some of the most beautifully accurate and tonally right classical guitar reproduction I've ever had from my stereo system was when I had a pair of Atma-Sphere M-60s on loan in the system. Relaxed and gorgeous. They put the great guitarist John Williams in the room.

Atmos-Sphere makes a 30 watt stereo amp that looks great. Havent heard it, but if its close to what the M-60s did, it may be the ticket. Perhaps Ralph can fill us in on the retail price.
Thanks, Oregonpapa. Over the years I've received and applied much advice from him and would readily listen to whatever he says. However, because of several pricey purchases I've recently made, consideration for purchase will have to be postponed. In the meantime I'll keep researching and listening with what I currently have which, btw, is not an altogether bad thing.
Looking at the specs, the speaker is rated at 92 db 2.83 volts/1 meter (being an 8 ohm load, the efficiency is the same). The minimum impedance is 6 ohms. This should be an easy speaker to drive and in most rooms 60 watts would be plenty of power.
Atmasphere, I, too found the published specs as 92dB sensitivity but there seems to be a very wide range of reports regarding the efficiency of these things. I was directed to a graph ( don't remember the origin) and it looks, at best, like the sensitivity is in the 84-85dB range. I also spoke with a local dealer who used to sell them who confirms the same thing. One way or the other, this temporary combination of the Prologue One at +/- 30W and the Reference 3A's does seem to work OK at least at lower volumes.
I've also read the speakers have been measured elsewhere and published sensitivity specs are not useful in this regard.

These are smaller monitors with extended bass Can't be very sensitive also. You can only have two of the three together at once.
Jim (Broadstone), 'twas I who referred earlier in this and other threads to these measurements of the currently produced Reference 3A MM de Capo BE, optimistically spec'd at 92 db and 8 ohms, and speculated that the sensitivity of your earlier Reference 3A model MIGHT be similar. That speculation seemingly having been confirmed by the dealer you spoke with.

The 86.7 db/2.83V/1m sensitivity for the MM de Capo BE that is reported in those measurements, btw, equates on a per watt basis to about 85.4 db/1W/1m in the mid-bass region (where lots of energy is typically required), given the speaker's impedance of about 6 ohms in that region.

That said, as you may have seen a few months ago in the long thread entitled "Building the Audio Note Kit 1 SET amp," member Rebbi achieved remarkably good results using that speaker with an 8 watt SET, albeit listening at modest volumes to mostly non-classical music. Eventually, though, he moved on to more efficient speakers. At least one other member whose inputs I consider to be especially credible, Brownsfan, also reported using those speakers with surprisingly good results using an 8 watt SET (the $6K Coincident Frankensteins), in his case mostly with classical music.

But personally I would not suggest going any lower than the 35W capability of the PL1, or perhaps the 30W capability of the Atmasphere S-30 (although I suspect that the M-60 would be a better match, in terms of impedance as well as in terms of power capability). Among the reasons I say that are the comments above by Tubegroover, Ralph/Atmasphere, and others, the somewhat large size of your room coupled with a greater than average listening distance, and my own philosophy that configuring a system in a manner that is marginal with respect to power should be avoided if at all possible.

Finally, one thing that might make the Atmasphere amps particularly worth considering, when and if your circumstances permit, is that based on all I have read about them I would expect they would provide extended and "fast" response in the treble region, with high frequency transients being reproduced in a "clean" and accurate manner, but without the overly bright sonic character that other wide bandwidth designs often seem have. All of which might result in their sonic character being a particularly suitable match for the hearing sensitivities you have described having.

Good luck. Best regards,
-- Al
Today I auditioned the Cary Rocket 88R for about 2 hours in my home and fell in absolute like with them. I was able to compare back and forth with the Primaluna Prologue One. The Prologues sound wonderful but I can't say enough about this 88R; I think I finally understand the meaning of effortless sound reproduction. I've been listening mainly in the triode mode but we went through many genres at low to high volumes back and forth between that and ultralinear and, even at high volumes the cats eyes never seemed to alter.

I like the latitude afforded with this amp, from 4 or 8 ohm out, linear or triode mode, bias adjustment, tube rolling, etc. but I have a lot of experimenting to do toward a more complete understanding of how best to set it up. The one thing I already know, though, is that this pairing of the amp with the Reference 3A's is magical with no doubt that this is the best sound my house has ever heard.

I'm still using the Peachtree Nova as a preamp and may start looking for another pre at some later time, but for the time being, I couldn't be more satisfied....I think.